It is known to provide a subsurface safety valve operated by solenoid coil. U.S. Pat. No. 3,731,742 discloses in one form a safety valve which is moved mechanically to the open position by a well tool and is locked in the open position by a detent. The valve is triggered to the closed position by actuating a solenoid for releasing the detent. U.S. Pat. No. 4,191,248 and U.S. Pat. No. Re. 30,110 disclosure subsurface solenoid actuated safety valves in which the solenoid mechanism performs the function of opening the valve and is fail-safe in that the valve will close in the event that electrical power is lost. However, these valves will undesirably close if various well forces overcome the power of the solenoid such as if the flow velocity through the well tubing increases or if well tools moving upwardly in the safety valve engage and cause the safety valve to close.
The present invention is directed to a failsafe subsurface well safety valve which is first opened by mechanically shifting a tubular member to open the safety valve, and secondly is locked in the open position by applying current to a solenoid coil which holds an armature to releasably lock the valve open. This has the advantage that the valve is positively locked open against forces in the well which might tend to close the valve and secondly allows the valve to be held open and in the locked position with a minimum of electrical energy.